In general, a circular knitting machine having a needle arranged movably upward on a peripheral surface of a tubular cylinder is used for forming a tubular knitting, for example, socks, gloves and sweaters. The tubular knitting is formed through feeding yarn while controlling the lifting operation of the needle on the peripheral surface of the cylinder.
With the use of the circular knitting machine for producing a tubular knitted fabric, the numbers of wale and the peripheral length are defined by the number of needles and the diameter of the cylinder. In order to form the tubular knitting with different numbers of wale and the peripheral length, the circular knitting machine equipped with various cylinders for the variation is required.
In order to form the tubular knitting with the long peripheral length, the diameter of the cylinder of the circular knitting machine is increased, thus enlarging the entire size of such machine.
The weft-knitting machine having a pair of longitudinally arranged front and rear needle beds with ends of the needles confronting each other, which is allowed to produce tubular knitted fabric of different diameters has been disclosed by the applicant of the present invention.
With the weft-knitting machine, when the carriage reciprocally movable on the needle bed is in the forward stroke, the yarn is fed to the needle of the needle bed to form the fabric at one side, and in the return stroke, the yarn is fed to the needle of the other needle bed such that the yarn for forming the fabric at one side is continued to form the fabric at the other side as shown in FIG. 5. The aforementioned fabric-forming course is repeatedly performed alternately to produce a tubular knitted fabric having both ends connected.
In the aforementioned case, upon transition from one needle bed to the other, the direction of the tension applied to the fed yarn changes as shown in FIG. 5. The needle of the needle bed at the edge of the fabric is likely to be pulled out. Once the needle is pulled out, the resultant loop becomes small.
The small loop may deteriorate quality of the tubular knitted product.
In order to cope with the aforementioned problem, the applicant of the present invention has proposed the art for producing a tubular knitted fabric using the weft-knitting machine equipped with a pair of needle beds arranged longitudinally, which allows the carriage to reciprocally move to connect both end portions of the fabric with the needle of the respective needle beds for producing the tubular knitted fabric. When the carriage is in the forward stroke where the needle is controlled to advance by the control cam for forming the knitted fabric, the needle advance preventing unit provided at both ends and/or closed to both ends is released to allow the needle to advance. When the carriage is in the return stroke, the needle advance preventing unit is enabled to allow the needle at both ends and/or close to both ends of the fabric to only retract (Patent Document 1).                Patent Document 1: Laid open Japanese Patent Application (Unexamined) Publication No. 86561/1993        